Rudy Giuliani’s account of Donald Trump’s role in the payment to Stormy Daniels has collapsed into near-incoherence.

In his latest interviews, the newly minted Trump lawyer has adopted a posture of impenetrable epistemological modesty — there’s nothing he knows about the case, or can possibly learn about it anytime soon. Giuliani retreated to this tack after directly contradicting the president’s denial of knowing anything about the hush money, and getting rebuked by Trump for being ill-informed and not yet up to speed.

It shouldn’t be this complicated. Getting their story straight would be much easier if they adopted a simple, nay simplistic, legal and political strategy — telling the truth.

Giuliani shocked the political world when he said last week that Trump had reimbursed his fixer Michael Cohen for the payout to the porn star. Rudy declared that this made it a private transaction, and therefore it couldn’t be a campaign-finance violation. Case closed.

But the legal reasoning wasn’t airtight — if Cohen made the payment to influence the campaign, it didn’t matter if Trump paid it back or not — and Trump wasn’t ready to endorse Rudy’s version of events.

By this past weekend, the former New York City mayor was on “This Week” on ABC News, incapable of saying much of anything at all. Had, George Stephanopoulos asked, Trump met Stormy Daniels? “It depends,” Giuliani replied, “on kind of what you mean by met her, right?”

When did Trump first learn Daniels asked for payment? “Don’t know and doesn’t matter to me.” Stephanopoulos pointed out that Giuliani told the website BuzzFeed that Cohen complained to Trump about not getting paid back after the 2016 campaign. So, the president knew about the payment after the campaign?

“Can’t say that,” Giuliani answered. Hadn’t Rudy stated it as fact in an interview? “Well, maybe I did,” he conceded. “I can just say it’s rumor. I can prove it’s rumor, but I can’t prove it’s fact. Yet. Maybe we will.”

Why did Trump deny knowledge of the payment on Air Force One on April 5? “Well, I don’t know.”

Rudy sounds like he’s been charged with unraveling one of the great mysteries of our time, when it’s all resolvable with about two questions: “Mr. President, when did you find out about the payment to Stormy Daniels? When did you pay Cohen back?” This is about a five-minute conversation.

Rudy is not limited by his ability to gather facts, but by the president’s willingness to be forthright. Although it would be painful — to the first lady, above all — Trump would be well-served to play it straight. He could make a vague confession about past conduct he’s not proud of; say that Cohen paid off Daniels to avoid embarrassment, with added motivation as the election approached (what Giuliani has been trying to say); and amend his campaign’s Federal Election Commission filing in an excess of caution.

It’s never ideal to admit to a possible violation of the law, even a technical one. But campaign-finance violations are rarely prosecuted, and current Justice Department guidance says that a sitting president can’t be indicted. This means that it is most important for Trump to win in the court of public opinion, and having a believable, consistent account is much better than basing a defense on a flat-out denial that no one believes, almost certainly not even Rudy or Trump’s other advocates.

Compared to the other allegations against Trump — collusion with the Russians, obstruction of justice — a decade-old affair is not a matter of great public import. But Bill Clinton showed how a president can parlay prideful denials, overconfidence in his ability to talk his way out of anything and personal embarrassment into a legal and constitutional conflagration. And, eventually, he had to tell the truth anyway.

Rudy Giuliani has had a rocky debut in his new role, but the ultimate problem here isn’t the counselor, but the client.

Rich Lowry can be reached via e-mail: comments.lowry@nationalreview.com.